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Mathematical physics
Mathematical physics is the scientific discipline concerned with the interface of mathematics and physics. There is no real consensus about what does or does not constitute mathematical physics. A very typical definition is the one given by the Journal of Mathematical Physics: "the application of mathematics to problems in physics and the development of mathematical methods suitable for such applications and for the formulation of physical theories."Definition from the Journal of Mathematical Physics.http://jmp.aip.org/jmp/staff.jsp This definition does, however, not cover the situation where results from physics are used to help prove facts in abstract mathematics which themselves have nothing particular to do with physics. This phenomenon has become increasingly important, with developments from string theory research breaking new ground in mathematics. Eric Zaslow coined the phrase physmatics to describe these developmentsZaslow E.,Physmatics, although other people would consider them as part of mathematical physics proper. Important fields of research in mathematical physics include: functional analysis/quantum physics, geometry/general relativity and combinatorics/probability theory/statistical physics. More recently, string theory has managed to make contact with many major branches of mathematics including algebraic geometry, topology, and complex geometry. Scope of the subject There are several distinct branches of mathematical physics, and these roughly correspond to particular historical periods. The theory of partial differential equations (and the related areas of variational calculus, Fourier analysis, potential theory, and vector analysis) are perhaps most closely associated with mathematical physics. These were developed intensively from the second half of the eighteenth century (by, for example, D'Alembert, Euler, and Lagrange) until the 1930s. Physical applications of these developments include hydrodynamics, celestial mechanics, elasticity theory, acoustics, thermodynamics, electricity, magnetism, and aerodynamics. The theory of atomic spectra (and, later, quantum mechanics) developed almost concurrently with the mathematical fields of linear algebra, the spectral theory of operators, and more broadly, functional analysis. These constitute the mathematical basis of another branch of mathematical physics. The special and general theories of relativity require a rather different type of mathematics. This was group theory: and it played an important role in both quantum field theory and differential geometry. This was, however, gradually supplemented by topology in the mathematical description of cosmological as well as quantum field theory phenomena. Statistical mechanics forms a separate field, which is closely related with the more mathematical ergodic theory and some parts of probability theory. The usage of the term 'Mathematical physics' is sometimes idiosyncratic. Certain parts of mathematics that initially arose from the development of physics are not considered parts of mathematical physics, while other closely related fields are. For example, ordinary differential equations and symplectic geometry are generally viewed as purely mathematical disciplines, whereas dynamical systems and Hamiltonian mechanics belong to mathematical physics. Prominent mathematical physicists One of the earliest mathematical physicists was the eleventh century Iraqi physicist and mathematician, Ibn al-Haytham 965-1039, known in the West as Alhazen. His conceptions of mathematical models and of the role they play in his theory of sense perception, as seen in his Book of Optics (1021), laid the foundations for mathematical physics. Other notable mathematical physicists at the time included Abū Rayhān al-Bīrūnī 973-1048 and Al-Khazini 1115-1130, who introduced algebraic and fine calculation techniques into the fields of statics and dynamics.Mariam Rozhanskaya and I. S. Levinova (1996), "Statics", p. 642, in In the first decade of the 16th century, amateur astronomer Nicholas Copernicus proposed heliocentrism, and published a treatise on it in 1543. Not quite radical, Copernicus merely sought to simplify astronomy and achieve orbits of more perfect circles, stated by Aristotelian physics to be the intrinsic motion of Aristotle's fifth element—the quintessence or universal essence known in Greek as aither for the English pure air—that was the pure substance beyond the sublunary sphere, and thus was celestial entities' pure composition. The German Johannes Kepler 1571–1630, Tycho Brahe's assistant, modified Copernican orbits to ellipses, however, formalized in the equations of Kepler's laws of planetary motion. An enthusiastic atomist, Galileo Galilei in his 1623 book The Assayer asserted that the "book of nature" is written in mathematics.Peter Machamer "Galileo Galilei"—sec 1 "Brief biography", in Zalta EN, ed, The Stanford Encyclopedia of Philosophy, Spring 2010 edn His 1632 book, upon his telescopic observations, supported heliocentrism.Antony G Flew, Dictionary of Philosophy, rev 2nd edn (New York: St Martin's Press, 1984), p 129 Having introducing experimentation, Galileo then refuted geocentric cosmology by refuting Aristotelian physics itself. Galilei's 1638 book Discourse on Two New Sciences established law of equal free fall as well as the principles of inertial motion, founding the central concepts of what would become today's classical mechanics. By the Galilean law of inertia as well as the principle Galilean invariance, also called Galilean relativity, for any object experiencing inertia, there is empirical justification of knowing only its being at relative rest or relative motion—rest or motion with respect to another object. René Descartes adopted Galilean principles and developed a complete system of heliocentric cosmology, anchored on the principle of vortex motion, Cartesian physics, whose widespread acceptance brought demise of Aristotelian physics. Descartes sought to formalize mathematical reasoning in science, and developed Cartesian coordinates for geometrically plotting locations in 3D space and marking their progressions along the flow of time.Antony G Flew, Dictionary of Philosophy, rev 2nd edn (New York: St Martin's Press, 1984), p 89 Prominent contributors to the 20th century's mathematical physics include Satyendra Nath Bose 1894–1974, Eugene Wigner 1902-1995, John von Neumann 1903-1957, Julian Schwinger 1918–1994, Sin-Itiro Tomonaga 1906–1979, Richard Feynman 1918–1988, Freeman Dyson 1923–, Jürgen Moser 1928-1999, Hideki Yukawa 1907–1981, Roger Penrose 1931–, Munir Ahmad Rashid 1934-, Vladimir Arnold 1937-2010, Stephen Hawking 1942–, Edward Witten 1951–, and Rudolf Haag 1922–. Yet mathematical physics is often traced to Archimedes in ancient Greece. Newtonian and post-Newtonian Isaac Newton 1642–1727 developed new mathematics, including calculus and several numerical methods such as Newton's method to solve problems in physics. Newton's theory of motion, published in 1687, modeled three Galilean laws of motion along with Newton's law of universal gravitation on a framework of absolute space—hypothesized by Newton as a physically real entity of Euclidean geometric structure extending infinitely in all directions—while presuming absolute time, supposedly justifying knowledge of absolute motion, the object's motion with respect to absolute space. The principle Galilean invariance/relativity was merely implicit in Newton's theory of motion. Having ostensibly reduced Keplerian celestial laws of motion as well as Galilean terrestrial laws of motion to a unifying force, Newton achieved great mathematic rigor if theoretical laxity.Imre Lakatos, auth, Worrall J & Currie G, eds, The Methodology of Scientific Research Programmes: Volume 1: Philosophical Papers (Cambridge: Cambridge University Press, 1980), pp 213-4, 220 In the 18th century, the Swiss Daniel Bernoulli 1700–1782 made contributions to fluid dynamics, and vibrating strings. The Swiss Leonhard Euler 1707–1783 did especial work in variational calculus, dynamics, fluid dynamics, and other areas. Also notable was the Italian-born Frenchman, Joseph-Louis Lagrange 1736–1813 for work in analytical mechanics (he formulated the so-called Lagrangian mechanics) and variational methods. The French mathematical physicist Joseph Fourier – 1830 introduced the notion of Fourier series to solve the heat equation giving rise to a new approach to handle partial differential equations by means of integral transforms. Into the early 19th century, the French Pierre-Simon Laplace 1749–1827 made paramount contributions to mathematical astronomy, potential theory, and probability theory. Siméon Denis Poisson 1781–1840 worked in analytical mechanics and potential theory. In Germany, Carl Friedrich Gauss 1777–1855 made key contributions to the theoretical foundations of electricity, magnetism, mechanics, and fluid dynamics. A couple of decades ahead of Newton's publication of a particle theory of light, the Dutch Christiaan Huygens 1629–1695 developed the wave theory of light, published in 1690. By 1804, Thomas Young's double-slit experiment revealed an interference pattern as though light were a wave, and thus Huygens's wave theory of light, as well as Huygens's inference that that light waves were vibrations of the luminiferous aether was accepted. Jean-Augustin Fresnel modeled hypothetical behavior of the aether. Michael Faraday introduced the theoretical concept of a field—not action at a distance. Mid-19th century, the Scottish James Clerk Maxwell 1831–1879 reduced electricity and magnetism to Maxwell's electromagnetic field theory, whittled down by others to the four Maxwell's equations. Initially, optics was found consequent of Maxwell's field. Later, radiation and then today's known electromagnetic spectrum were found also consequent of this electromagnetic field. Maxwell's countryman Lord Kelvin 1824–1907 made substantial discoveries in thermodynamics. Among British physicists, Lord Rayleigh 1842–1919 worked on sound; George Gabriel Stokes 1819–1903 was a leader in optics and fluid dynamics; Irishman William Rowan Hamilton 1805–1865 did notable work on analytical mechanics finding out a new and powerful approach nowadays known as hamiltonian mechanics. Very relevant contributions to this approach are due to his German colleague Carl Gustav Jacobi 1804–1851 in particular referring to the so-called canonical transformations. The German Hermann von Helmholtz 1821–1894 is greatly contributed to electromagnetism, waves, fluids, and sound. In the United States, the pioneering work of Josiah Willard Gibbs 1839–1903 became the basis for statistical mechanics. Fundamental theoretical results in this area were achieved by the German Ludwig Boltzmann 1844-196. Together, these individuals laid the foundations of electromagnetic theory, fluid dynamics, and statistical mechanics. Relativistic By the 1880s, prominent was the paradox that an observer within Maxwell's electromagnetic field measured it at approximately constant speed regardless of the observer's speed relative to other objects within the electromagnetic field. Thus, although the observer's speed was continually lost relative to the electromagnetic field, it was preserved relative to other objects in the electromagnetic field. And yet no violation of Galilean invariance within physical interactions among objects was detected. As Maxwell's electromagnetic field was modeled as oscillations of the aether, physicists inferred that motion within the aether resulted in aether drift, shifting the electromagnetic field, explaining the observer's missing speed relative to it. Physicists' mathematical process to translate the positions in one reference frame to predictions of positions in another reference frame, all plotted on Cartesian coordinates, had been the Galilean transformation, which was newly replaced with Lorentz transformation, modeled by the Dutch Hendrik Lorentz 1853–1928. In 1887, experimentalists Michelson and Morley failed to detect aether drift, however. It was hypothesized that motion into the aether prompted aether's shortening, too, as modeled in the Lorentz contraction. Hypotheses at the aether thus kept Maxwell's electromagnetic field aligned with the principle Galilean invariance across all inertial frames of reference, while Newton's theory of motion was spared. In the 19th century, Gauss's contributions to non-Euclidean geometry, or geometry on curved surfaces, laid the groundwork for the subsequent development of Riemannian geometry by Bernhard Riemann 1826–1866. Austrian theoretical physicist and philosopher Ernest Mach criticized Newton's postulated absolute space. Mathematician Jules-Henri Poincaré 1854–1912 questioned even absolute time. In 1905, Pierre Duhem published a devastating criticism of the foundation of Newtown's theory of motion. Also in 1905, Albert Einstein 1879–1955 published special theory of relativity, newly explaining both the electromagnetic field's invariance and Galilean invariance by discarding all hypotheses at aether, including aether itself. Refuting the framework of Newton's theory—absolute space and absolute time—special relativity states relative space and relative time, whereby length contracts and time dilates along the travel pathway of an object experiencing kinetic energy. In 1908, Einstein's former professor Hermann Minkowski modeled 3D space together with the 1D axis of time by treating the temporal axis like a fourth spatial dimension—altogether 4D spacetime—and declared the imminent demise of the separation of space and time. Einstein initially called this "superfluous learnedness", but later used Minkowski spacetime to great elegance in general theory of relativity,Salmon WC & Wolters G, eds, Logic, Language, and the Structure of Scientific Theories (Pittsburgh: University of Pittsburgh Press, 1994), p 125 extending invariance to all reference frames—whether perceived as inertial or as accelerated—and thanked Minkowski, by then deceased. General relativity replaces Cartesian coordinates with Gaussian coordinates, and replaces Newton's claimed empty yet Euclidean space traversed instantly by Newton's vector of hypothetical gravitational force—an instant action at a distance—with a gravitational field. The gravitational field is Minkowski spacetime itself, the 4D topology of Einstein aether modeled on a Lorentzian manifold that "curves" geometrically, according to the Riemann curvature tensor, in the vicinity of either mass or energy. (By special relativity—a special case of general relativity—even massless energy exerts gravitational effect by its mass equivalence locally "curving" the geometry of the four, unified dimensions of space and time.) Quantum Another revolutionary development of the twentieth century has been quantum theory, which emerged from the seminal contributions of Max Planck 1856–1947 (on black body radiation) and Einstein's work on the photoelectric effect. This was, at first, followed by a heuristic framework devised by Arnold Sommerfeld 1868–1951 and Niels Bohr 1885–1962, but this was soon replaced by the quantum mechanics developed by Max Born 1882–1970, Werner Heisenberg 1901–1976, Paul Dirac 1902–1984, Erwin Schrödinger 1887–1961, and Wolfgang Pauli 1900–1958. This revolutionary theoretical framework is based on a probabilistic interpretation of states, and evolution and measurements in terms of self-adjoint operators on an infinite dimensional vector space. That is the so-called Hilbert space, introduced in its elementary form by David Hilbert 1862–1943 and Frigyes Riesz 1880-1956, and rigorously defined within the axiomatic modern version by John von Neumann in his celebrated book on mathematical foundations of quantum mechanics, where he built up a relevant part of modern functional analysis on Hilbert spaces, the spectral theory in particular. Paul Dirac used algebraic constructions to produce a relativistic model for the electron, predicting its magnetic moment and the existence of its antiparticle, the positron. Mathematically rigorous physics The term ' 'mathematical' ' physics is also sometimes used in a special sense, to distinguish research aimed at studying and solving problems inspired by physics within a mathematically rigorous framework. Mathematical physics in this sense covers a very broad area of topics with the common feature that they blend pure mathematics and physics. Although related to theoretical physics, 'mathematical' physics in this sense emphasizes the mathematical rigour of the same type as found in mathematics. On the other hand, theoretical physics emphasizes the links to observations and experimental physics which often requires theoretical physicists (and mathematical physicists in the more general sense) to use heuristic, intuitive, and approximate arguments. Such arguments are not considered rigorous by mathematicians. Arguably, rigorous mathematical physics is closer to mathematics, and theoretical physics is closer to physics. Such mathematical physicists primarily expand and elucidate physical theories. Because of the required rigor, these researchers often deal with questions that theoretical physicists have considered to already be solved. However, they can sometimes show (but neither commonly nor easily) that the previous solution was incorrect. The field has concentrated in three main areas: (1) quantum field theory, especially the precise construction of models; (2) statistical mechanics, especially the theory of phase transitions; and (3) nonrelativistic quantum mechanics (Schrödinger operators), including the connections to atomic and molecular physics. The effort to put physical theories on a mathematically rigorous footing has inspired many mathematical developments. For example, the development of quantum mechanics and some aspects of functional analysis parallel each other in many ways. The mathematical study of quantum statistical mechanics has motivated results in operator algebras. The attempt to construct a rigorous quantum field theory has brought about progress in fields such as representation theory. Use of geometry and topology plays an important role in string theory. The above are just a few examples. An examination of the current research literature would undoubtedly give other such instances. Notes References * * Bibliographical references The classics :* :* :* :* (pbk.) :* (softcover) :* :* :*''This is a'' reprint'' of the second (1980) edition of this title.'' :* :*''This is a reprint of the'' 1956 second edition. :* :*''This is a'' reprint'' of the original (1953) edition of this title.'' :* :* :* :*''This tome was reprinted in 1985.'' :* :* :* Textbooks for undergraduate studies :* (pbk.) :* :* :* :* :* (set : pbk.) Other specialised subareas :* :* (pbk.) :* (pbk.) :* :* :* (pbk.) See also * Important publications in Mathematical Physics * Theoretical physics External links * Communications in Mathematical Physics * Journal of Mathematical Physics * Mathematical Physics Electronic Journal * International Association of Mathematical Physics * Erwin Schrödinger International Institute for Mathematical Physics * [http://eqworld.ipmnet.ru/en/solutions/lpde.htm Linear Mathematical Physics Equations: Exact Solutions] - from EqWorld * [http://eqworld.ipmnet.ru/en/solutions/eqindex/eqindex-mphe.htm Mathematical Physics Equations: Index] - from EqWorld * [http://eqworld.ipmnet.ru/en/solutions/npde.htm Nonlinear Mathematical Physics Equations: Exact Solutions] - from EqWorld * [http://eqworld.ipmnet.ru/en/methods/meth-pde.htm Nonlinear Mathematical Physics Equations: Methods] - from EqWorld Category:Mathematical physics Category:Mathematical science occupations